Every second, tens of billions of neutrinos produced by nuclear fusion in the sun pass through every square centimeter of Earth—and through our bodies—almost without interacting. Although they are among the most abundant particles emitted by the sun, their extremely weak interactions make detecting these elusive particles one of the greatest experimental challenges in particle physics. A number of specialized neutrino detectors are in operation around the world, exploiting the unique properties of neutrinos to investigate astrophysical phenomena.